Optical excitations of a few charges in cuprates

Thomas, G. A.; Rapkine, D. H.; Cooper, S. L.; Cheong, Sang‐Wook; Cooper, A. S.; Schneemeyer, Lynn; Waszczak, J. V.

doi:10.1103/physrevb.45.2474

Cited by 100 publications

(56 citation statements)

References 35 publications

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“…6,7 (d) Near the optimal doping, the high mid-infrared peak around ω H mir continuously evolves into an approximate 1/ω behavior in the optical conductivity, with a shift of spectral weight towards lower energy. 5,8 At the same time, the scattering rate shows a linear-ω dependence, 9,10 while the scattering rate at ω ∼ 0 increases linearly with temperature, consistent with the dc resistivity measurement.…”

Section: Introductionmentioning

confidence: 99%

Charge dynamics in the phase string model for high-Tcsuperconductors

Weng

2007

Phys. Rev. B

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An understanding of the anomalous charge dynamics in the high-Tc cuprates is obtained based on a model study of doped Mott insulators. The high-temperature optical conductivity is found to generally have a two-component structure: a Drude like part followed by a mid-infrared band. The scattering rate associated with the Drude part exhibits a linear-temperature dependence over a wide range of high temperature, while the Drude term gets progressively suppressed below a characteristic energy of magnetic origin as the system enters the pseudogap phase. The high-energy optical conductivity shows a resonancelike feature in an underdoped case and continuously evolves into a 1/ω tail at higher doping, indicating that they share the same physical origin. In particular, such a high-energy component is closely correlated with the ω-peak structure of the density-density correlation function at different momenta, in systematic consistency with exact diagonalization results based on the t-J model. The underlying physics is attributed to the high-energy spincharge separation in the model, in which the "mode coupling" responsible for the anomalous charge properties is not between the electrons and some collective mode but rather between new charge carriers, holons, and a novel topological gauge field controlled by spin dynamics, as the consequence of the strong short-range electron-electron Coulomb repulsion in the doped Mott insulator.

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Section: Introductionmentioning

confidence: 99%

Charge dynamics in the phase string model for high-Tcsuperconductors

Weng

2007

Phys. Rev. B

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“…56 A power-law dependence of conductivity on frequency was ascribed to thermally assisted tunneling between localized states. 56 Several broad absorption features in the midinfrared have been reported for a number of low doped cuprates 47,57 and have been successfully modeled as small polarons bound to impurities. 58 A combined NMR and NQR study of La 2 CuO 4+y with y in the range 0.06-0.12, 59 showed that an additional line in the copper NQR spectrum of La 2 CuO 4+y could be assigned to a hole pinned to the lattice.…”

Section: B Low Hole-density Limitmentioning

confidence: 99%

“…57 The binding energy of the hole to interstitial oxygen ions in La 2 CuO 4+y was determined to be 35 meV from Hall measurements. 56 A power-law dependence of conductivity on frequency was ascribed to thermally assisted tunneling between localized states.…”

Section: B Low Hole-density Limitmentioning

confidence: 99%

Small polarons and magnetic antiphase boundaries inCa2−xNaxCuO2Cl
Patterson
¹

2008
Phys. Rev. B
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We report hybrid density functional theory calculations on hole doped Ca 2−x Na x CuO 2 Cl 2 performed in 4 ϫ 4, 4 ͱ 2 ϫ 4 ͱ 2, and 8 ϫ 2 supercells with hole concentrations x = 0.0625 and x = 0.125. Holes at the lower concentration form small polarons, in which the hole is mainly localized on four oxygen ions surrounding one copper ion. The polaron is a spin one-half ferromagnetic polaron ͑Cu 5 O 4 ͒, in which the moment on the central copper ion is parallel to those on the four neighboring copper ions and the moment on the oxygen ions is opposed to that on the copper ions. This is therefore an Emery-Reiter spin polaron rather than a Zhang-Rice singlet. At the higher hole concentration ͑x = 0.125͒, many cuprates form stripes. Hybrid density functional theory calculations on linear chains of spin polarons separated by 4a 0 show a group of bands localized mainly on the stripe. Spins on neighboring copper ions in the stripe are parallel and so the stripe forms a magnetic antiphase boundary between antiferromagnetically ordered blocks of copper spins. Stripes of this kind, which run in one direction only, may explain recent scanning tunneling microscopy data from Ca 2−x Na x CuO 2 Cl 2 by Kohsaka et al. ͓Science 315, 1380 ͑2007͔͒. We also consider an ordered spin polaron phase where magnetic antiphase boundaries intersect at right angles. In this case, sets of four copper ions in squares at stripe intersections have parallel spins. This phase may be the 4 ϫ 4 checkerboard pattern reported by Hanaguri et al. ͓Nature ͑London͒ 430, 1001 ͑2004͔͒.

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“…4 The mid-infrared band was also observed for nonstoichiometric cuprates of Nd 2 CuO 4−y and La 2 CuO 4+y with some vacancies on oxygen sites. 5 Exact diagonalization calculations on small clusters verified the existence of the mid-infrared band upon doping holes away from half filling. [6][7][8] Nonmagnetic impurities embedded in the high-T c cuprates have been used to investigate transport and magnetic properties of the cuprates.…”

Section: Introductionmentioning

confidence: 99%

Effects of nonmagnetic impurities on optical conductivity in strongly correlated systems

1999

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Effects of nonmagnetic impurities on optical conductivity in the systems of antiferromagnetically correlated electrons are examined based on the Lanczos exact diagonalization scheme. As a result of resonant scattering a lowfrequency peak in the optical conductivity is predicted to occur in the presence of the nonmagnetic impurities, which is consistent with the observed normalstate optical conductivity of YBa 2 (Cu 1−x Zn x ) 3 O 7−δ . In addition, a relatively high and broad peak is found to occur at a high frequency region as a consequence of the Heisenberg interaction between electrons, in agreement with observation in the peak position.

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Optical excitations of a few charges in cuprates

Cited by 100 publications

References 35 publications

Charge dynamics in the phase string model for high-Tcsuperconductors

Charge dynamics in the phase string model for high-Tcsuperconductors

Small polarons and magnetic antiphase boundaries inCa2−xNaxCuO2Cl
Patterson
¹

2008
Phys. Rev. B
18
0
9
0
View full text Add to dashboard Cite

Effects of nonmagnetic impurities on optical conductivity in strongly correlated systems

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Optical excitations of a few charges in cuprates

Cited by 100 publications

References 35 publications

Charge dynamics in the phase string model for high-Tcsuperconductors

Charge dynamics in the phase string model for high-Tcsuperconductors

Small polarons and magnetic antiphase boundaries inCa2−xNaxCuO2ClPatterson1 2008Phys. Rev. B18090View full textAdd to dashboardCite

Effects of nonmagnetic impurities on optical conductivity in strongly correlated systems

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Small polarons and magnetic antiphase boundaries inCa2−xNaxCuO2Cl
Patterson
¹

2008
Phys. Rev. B
18
0
9
0
View full text Add to dashboard Cite